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Isabelle Viktoria Maciohsek
2020-10-20 23:02:01 +03:00
parent 52880f08ee
commit caa67e2a49
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snippets/invertKeyValues.md
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@ -1,12 +1,13 @@
---
title: invertKeyValues
tags: object,intermediate
tags: object,advanced
---
Inverts the key-value pairs of an object, without mutating it. The corresponding inverted value of each inverted key is an array of keys responsible for generating the inverted value. If a function is supplied, it is applied to each inverted key.
Inverts the key-value pairs of an object, without mutating it.
- Use `Object.keys()` and `Array.prototype.reduce()` to invert the key-value pairs of an object and apply the function provided (if any).
- Omit the second argument, `fn`, to get the inverted keys without applying a function to them.
- The corresponding inverted value of each inverted key is an array of keys responsible for generating the inverted value. If a function is supplied, it is applied to each inverted key.
```js
const invertKeyValues = (obj, fn) =>
@ -20,5 +21,6 @@ const invertKeyValues = (obj, fn) =>
```js
invertKeyValues({ a: 1, b: 2, c: 1 }); // { 1: [ 'a', 'c' ], 2: [ 'b' ] }
invertKeyValues({ a: 1, b: 2, c: 1 }, value => 'group' + value); // { group1: [ 'a', 'c' ], group2: [ 'b' ] }
invertKeyValues({ a: 1, b: 2, c: 1 }, value => 'group' + value);
// { group1: [ 'a', 'c' ], group2: [ 'b' ] }
```